Boiler Losing Pressure
Your boiler pressure gauge shows pressure below 1 bar, or keeps dropping and needs frequent topping up. This affects heating and hot water performance.
⚠️ Urgent - Don't DelayCommon Causes
Small leak somewhere in the system (most common)
Recently bled radiators
Faulty pressure relief valve
Expansion vessel needs recharging
Leak at radiator valve or fitting
Microleaks invisible to the eye
System hasn't been topped up after work
Signs of Pressure Problems
Pressure gauge below 1 bar (or in red zone)
Boiler lockout with low pressure error code
Need to top up pressure more than twice a year
Visible leaks at radiators or pipes
Wet patches appearing under boiler
Water staining on ceilings (leak in system)
Hearing filling loop running when it shouldn't
🚨 What Happens If You Ignore This?
Persistent low pressure indicates a leak somewhere, causing ongoing water damage and potentially serious problems. The boiler will eventually stop working entirely.
Diagnosing Pressure Loss
Check the Pressure Gauge
Normal operating pressure is 1-1.5 bar when cold, rising to 2 bar when hot. Below 1 bar = needs topping up. Above 3 bar = overpressured.
Inspect for Visible Leaks
Check all radiator valves, pipe connections, and under the boiler. Look for drips, staining, or green corrosion marks.
Check the Pressure Relief Pipe
Find the copper pipe exiting through your wall from the boiler. If it's wet or has white limescale marks, the PRV may be discharging.
⚠️ Safety: Don't interfere with the PRV - it's a safety device.
Note How Often You Top Up
Once after bleeding radiators is normal. Monthly topping up suggests a small leak. Weekly suggests a significant leak.
⚠️ Call a Professional If You Notice:
- •Topping up more than twice per year
- •You can't find any visible leak
- •Pressure drops rapidly (hours not weeks)
- •Water is dripping from the boiler itself
- •Boiler is showing error codes
- •You're uncomfortable using the filling loop
- •The problem started after recent work
Solutions
🔧 DIY Solution
Difficulty: easy
- 1
Locate the filling loop (flexible braided hose under or near boiler)
- 2
Ensure both filling loop valves are fully closed
- 3
Watch the pressure gauge
- 4
Slowly open one valve, then the other
- 5
Watch pressure rise to 1.5 bar (no higher)
- 6
Close both valves firmly
- 7
If external filling loop, disconnect one end after topping up
👷 Professional Solution
We'll pressure test the system to find leaks, check the expansion vessel, and inspect the PRV. For hidden leaks, we use thermal imaging and specialist detection.
Maintaining Boiler Pressure
Check pressure monthly - catch drops early
After bleeding radiators, top up pressure
Annual boiler service includes pressure system check
Don't ignore small leaks - they worsen
Have expansion vessel checked every few years
Use inhibitor to prevent internal corrosion
Frequently Asked Questions
Find answers to common questions about our services.
Still have questions? We're here to help.
Contact UsStill Having Problems?
If you've tried the DIY solutions and still have issues, or if you'd prefer a professional to handle it from the start, we're here to help.
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